【摘要】 体外在常规反应条件下,粉防已碱（Tet）对大鼠心肌微粒体Na⁺,K⁺-ATPase活性无明显影响,但浓度依赖性抑制Mg²⁺-ATPase(IC₅₀=179μmol/L).Tet 10和100μmol/L使哇巴因（Oua）抑制Na⁺,K⁺-ATPase的量效曲线平行右移.Tet 100μmol/L可显著提高低K⁺或高Ca²⁺浓度时的Na⁺,K⁺-ATPase活性,但未能明显增加低Na⁺浓度时该酶的活性.动力学分析提示Tet 100μmol/L增加Na⁺,K⁺-ATPase对ATP的亲和力,但不改变其最大反应速度。更多还原

【Abstract】 The effect of tetrandrine （Tet）on Na⁺, K⁺ -ATPase and Mg²⁺-ATPase in rat myocardial microsomes was investigated in vitro. Under optimal condition, Tet did not influence Na⁺, K⁺ - ATPase activity but concentration- dependently inhibited Mg²⁺ - ATPase with an IC₅₀ of 179 μmol/L. At 10 or 100 μmol/L, Tet caused the concentration- inhibition curves for ouabain a parallel shift to the fight. Tet 100 μmol/L markedly increased the activity of Na⁺, K⁺ -ATPase under suboptimal K⁺ or excessive Ca²⁺ condition. However, it did not significantly increase the enzyme activity when the Na⁺ concentration was lower. A kinetic analysis showed that Tet increased the affinity of Na⁺, K⁺- ATP ase to ATP, but did not change the maximal velocity of the enzyme reaction.更多还原